document.write( "Question 1151193: I drove to my parents' house at $40$ miles per hour. If I had driven 30 miles an hour instead, then I would have gotten there 20 minutes later. How many miles did I drive? \n" ); document.write( "
Algebra.Com's Answer #772856 by greenestamps(13203) You can put this solution on YOUR website! \n" ); document.write( "The solution method shown by tutor @josgarithmetic is a perfectly good standard algebraic method. \n" ); document.write( "If you are one of many who dislike working with fractions, here is a very different, somewhat informal method. \n" ); document.write( "The ratio of the two speeds is 40:30 = 4:3; since the distances are the same, the ratio of the times is 3:4. \n" ); document.write( "Given that ratio of times, let the two times be 3x and 4x. The difference, 4x-3x=x, is 20 minutes. \n" ); document.write( "That means the amount of time at 40mph was 3x = 3(20 minutes) = 60 minutes = 1 hour. And 40mph for 1 hour makes the distance 40 miles. \n" ); document.write( " \n" ); document.write( " |